Publication Date


Document Type


First Advisor

Ervin, C. Patrick

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Geology


Gravity anomalies--Wisconsin--Mathematical models; Batholiths--Wisconsin--Mathematical models


Recently acquired gravity data have more extensively delineated the approximately -30 mGal Bouguer gravity anomaly associated with the Wolf River Batholith, which outcrops in northeast Wisconsin. This anomaly is superimposed on the Wisconsin Gravity Minimum, a -60 mGal Bouguer anomaly over the Wisconsin Arch. The gravity field was upward continued to eliminate short-wavelength, shallow anomalies that tend to mask the field associated with the batholith. A second filter was applied to minimize the affect of the Wisconsin arch in the area associated with the Wolf River Batholith. Modeling of the filtered gravity field indicates that the batholith has a variable thickness, averaging between 1.5 and 2 km thick. This model supports the theory that the batholith was emplaced at relatively shallow depths (less than 4 km), and that it is fairly thin. The model also supports the characteristics of an epizonal batholith. According to the model, the batholith does not extend far past its western, eastern,and northern outcrops, but does extend a considerable distance in the subsurface beyond its southern boundary. Although the Wisconsin Gravity Minimum reaches its most negative value over the batholith, the Wolf River Batholith is not fully coincident with nor the sole cause of the Wisconsin Minimum.


Includes bibliographical references (pages 77-81)


viii, 97 pages




Northern Illinois University

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